1. Field of the Invention
The present invention relates to an electrical equipment casing that achieves both of enhanced heat dissipation and a size reduction of a reactor which is a heater part incorporated therein.
2. Related Art
Recently, automobiles furnished with an idle-stop function that stops engine driving when the automobiles are stationary or automobiles incorporating electrical power steering that reduces an engine load are made available in consideration of environmental friendliness and from the viewpoint of improvement of fuel efficiency. Also, a hybrid system that actively assists engine driving, a regenerative braking system that recovers braking energy as electric energy during vehicle braking and the like are attracting attention. In the context of the foregoing, electric power the automobiles need tends to increase and there has been proposed a configuration to provide a DC-to-DC convertor that generates electric power at high efficiency by setting a generated voltage of a generator high and steps down the voltage to a battery voltage.
In a DC-to-DC convertor, which is electrical equipment that controls a large current, one of chief heat releasing sources is a reactor. In order to enhance heat releasing efficiency of the reactor, heat dissipation is enhanced by housing the reactor in a casing having high heat conductivity or by molding the reactor from insulating resin having high heat conductivity. In this regard, a technique of enhancing heat dissipation of the reactor is now proposed, for example, in Patent Document 1. In electrical equipment in the related art provided with a reactor integral with a heat sink, the heat sink has a reactor housing portion. Accordingly, thermal resistance such that occurs in a configuration in which a heat transfer path bridges from one part to another different part does not exist. It thus becomes possible to enhance heat releasing efficiency of the reactor.    Patent Document 1: JP-A-2011-41397
With the casing structure described in Patent Document 1, it does become possible to enhance heat dissipation of the reactor. However, because a dimension of radiator fins provided to the heat sink is added to the reactor housing portion, this structure has a problem that the overall casing increases in size.